Concomitant occurrence of facial cutaneous and parotid gland metastases from rectal cancer after preoperative chemoradiotherapy

Background: Unusual sites of metastasis to the parotid gland and face are reported in patients with colorectal cancer, but the localization to both sites at the same time has never been described so far. Case Report: Here, we describe the case of a 76-year-old woman with a T3N1M0 G2 rectal adenocarcinoma, treated with preoperative chemoradiotherapy performed at suboptimal dosages due to unacceptable toxicity. At the end of the program, the re-staging demonstrated the presence of metastasis in both the left parotid gland and subcutaneously on the frontal region of her face while the primary locoregional tumour manifestation was radiologically down-staged (reduction in N staging from N1 to N0). The patient did not respond to any other treatment and died due to disease progression 15 months after the diagnosis. Conclusions: Metastatic tumours in the parotid gland are uncommon with a higher incidence of primary sites of the head and neck. Parotid involvement of rectal adenocarcinoma is also extremely rare, and concomitant involvement of both the parotid gland and the face was not previously described. In this case, we cannot rule out the hypothesis that the delay of surgical removal of the primary tumour and/or a specific action of concomitant chemoradiotherapy on the tumour cell phenotype could promote cancer cell spreading to unusual sites.